The crystallinity and composition of superior thin g-C3N4 nanosheets were adjusted at different temperature settings to study property evolution via a two-step thermal polymerization procedure. g-C3N4 sample prepared at 600 °C shows high N/C ratio and amorphous structure while a crystalline g-C3N4 sample with C/N ratio of nearly 0.75 was obtained at 750 °C. The band gap varies for each type of g-C3N4 sample and photodegradation kinetics were examined to be related to the crystallinity of the g-C3N4 sample. The RhB photocatalytic degradation plots for g-C3N4 nanosheets samples prepared at more than 600 °C are fitted using the pseudo-first-order model while the reaction for bulk g-C3N4 sample prepared at 550 °C follows zero-order kinetics. This phenomenon is ascribed to the varying surface states of the g-C3N4 samples. g-C3N4 nanosheets prepared at 700 °C showed the best photocatalytic performance, in which the sample with both amorphous and crystalline structural features is assumed to be amorphous/crystalline homojunctions. Moreover, Pt deposition confirms that g-C3N4 nanosheets prepared at 700 °C reveal the highest photocatalytic H2 evolution rate of 4892 μmol/hg which is about 21 times high compared with amorphous g-C3N4 nanosheets prepared at 600 °C.

中文翻译：

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超细 g-C3N4 纳米片及其结晶度和 Pt 沉积的光化学性质演变


在不同温度设置下调整优质薄 g-C3N4 纳米片的结晶度和组成，以通过两步热聚合程序研究性能演变。在 600 °C 下制备的 g-C3N4 样品显示出较高的 N/C 比和无定形结构，而在 750 °C 下制备的结晶 g-C3N4 样品的 C/N 比接近 0.75。 每种类型的 g-C3N4 样品的带隙都不同，并且检查了光降解动力学与 g-C3N4 样品的结晶度有关。在超过 600 °C 下制备的 g-C3N4 纳米片样品的 RhB 光催化降解图使用准一级模型进行拟合，而在 550 °C 下制备的块状 g-C3N4 样品的反应遵循零级动力学。这种现象归因于 g-C3N4 样品的不同表面状态。在 700 °C 下制备的 g-C3N4 纳米片显示出最佳的光催化性能，其中具有非晶和结晶结构特征的样品被假设为非晶/结晶同结。此外，Pt 沉积证实，在 700 °C 下制备的 g-C3N4 纳米片显示出最高的光催化 H2 释放速率，为 4892 μmol/hg，与在 600 °C 下制备的无定形 g-C3N4 纳米片相比，高出约 21 倍。